from retrying import retry
import requests
from loguru import logger
import random, time #2020-03-04添加

class BaseCrawler(object):
    urls = []

    # 2020-03-04修改，使用用户代理（其实也不是用户代理的原因）
    user_agent_list = [
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/82.0.4056.3 Safari/537.36",
        "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",
        "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",
        "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",
        "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
        "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",
    ]
    
    @retry(stop_max_attempt_number=3, retry_on_result=lambda x: x is None)
    def fetch(self, url, **kwargs):
        User_Agent = random.choice(self.user_agent_list)
        header = {'User-Agent': User_Agent}
        try:
            response = requests.get(url, headers=header, **kwargs)
            time.sleep(1) #这个解决了真正的问题（出现了503错误）
            if response.status_code == 200:
                return response.text
            # 2020-03-04添加
            else:
                print("ERROR: 网络连接失败！ status: %s url: %s" % (response.status_code, url))
        except requests.ConnectionError:
            return
    
    @logger.catch
    def crawl(self):
        """
        crawl main method
        """
        for url in self.urls:
            logger.info(f'fetching {url}')
            html = self.fetch(url)
            for proxy in self.parse(html):
                logger.info(f'fetched proxy {proxy.string()} from {url}')
                yield proxy
